1. The Field of the Invention
This invention relates to visual signalling devices utilized in combination with other similar signalling devices and more particularly to that class having automatic synchronization devices facilitating automatic synchronization of the components thereof.
2. Description of the Prior Art
The prior art abounds with signalling devices for displaying a plurality of messages. U.S. Pat. No. 3,201,785 issued Aug. 17, 1965 to A. E. Knotowicz discloses an indicating device utilizing a plurality of regularly located solenoid coils operating on a permanent mgnet pivotably secured thereinbetween. The permanent magnet is afixed to a drum disposed on the outermost regions of the solenoid coils. A switch arrangement is provided such that upon energizing the appropriate solenoid coil the magnet orients itself in accordance with the location of the selectively energized coil thereby rotating the wheel to a selected position displaying the indicia located in the outermost regions thereof. Such device is capable of displaying a plurality of indicia sites but is ineffective when such plurality is great in number.
U.S. Pat. No. 2,635,227 issued Apr. 4, 1953 to F. Liotta teaches a motor operated elongated cube whose surfaces each carry indicia. Operating the motor displaces the cube in a preferred location such that one surface thereof is disposed adjacent a viewing window in a housing carrying the cube. Light sources are located within the cube and are utilized to emanate light rays, passing through the translucent or transparent indicia carrying cube outwardly from the window of the apparatus. This device suffers the deficiency of only providing four discrete message units capable of being displayed on four adjacent surfaces distributed about the axis of revolution of the cube.
U.S. Pat. No. 3,226,707 issued Dec. 28, 1965 to H. Newman et al discloses a pair of reels, each carrying one end of a elongated strip upon which indicia is disposed. A light source, carried within a housing, similarly carrying the reels and strip, emanates light beams, passing through the strip, terminating on a transparent or translucent window-like opening disposed on one surface of the housing. A plurality of light sources arranged in specific locations, coupled with a motor drive for the elongated strip and a flasher, permits a plurality of displays to emanate outwardly from the display portion of the apparatus. A control box, also provided with individual illumination sources, is operated by a plurality of independent switches such that each light source illuminates a screen upon which companion indicia carrying area is illuminated. Thus, the user is capable of viewing at a remote location, the messages being displayed by the display unit, such messages being motor operated. This apparatus, though utilizing a remote indicator carrying the same message elements as the display indicator, is limited in value by virtue of the fact that the remote indicator and the display indicator can only display a discreet number of messages as a function of the number of switches and light sources used therein. Cost increases in a direct ratio with the number of switches and hence with the number of messages that can be displayed.